SPC AC 080543

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1243 AM CDT Sat Jul 08 2023

   Valid 081200Z - 091200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY INTO TONIGHT
   ACROSS PARTS OF EASTERN COLORADO...NORTHEASTERN NEW
   MEXICO...SOUTHWESTERN KANSAS...WESTERN AND SOUTHERN
   OKLAHOMA...NORTHWESTERN AND NORTHERN TEXAS...MUCH OF ARKANSAS...THE
   MISSOURI BOOTHEEL...SOUTHWESTERN KENTUCKY...WESTERN
   TENNESSEE...NORTHERN AND CENTRAL MISSISSIPPI AND ADJACENT PORTIONS
   OF WESTERN ALABAMA...

   ...SUMMARY...
   Scattered strong to severe thunderstorms, and one or two organized
   thunderstorm clusters, are possible east of the Front Range and
   Sangre de Cristo Mountains through the Texas and Oklahoma Panhandles
   and Red River Valley vicinity.  Additional strong to severe
   thunderstorm development is possible across parts of the lower
   Mississippi into Ohio Valleys.

   ...Synopsis...
   Perhaps most prominently in mid/upper levels, models indicate that
   blocking mid-level ridging will become increasingly prominent to the
   south of Greenland, with a pair of flanking, broad and anamalously
   deep closed lows.  The center of the western one is forecast to
   redevelop west/southwest of Hudson Bay into northeastern Manitoba,
   with cyclonic flow strengthening on its western periphery, across
   the eastern Canadian Prairies. 

   At the same time, relatively amplified, but weak, split flow is
   forecast to persist across the eastern Pacific into western North
   America.  Mid-level ridging in one branch appears likely to build
   across the eastern Great Basin, in advance of mid-level troughing
   approaching the Pacific coast.  Downstream, broadly cyclonic and
   northwesterly flow  will prevail from the lee of the Front Range and
   Sangre de Cristo Mountains into larger-scale troughing digging
   across the lower Mississippi Valley, more or less in phase with
   troughing digging across the Upper Midwest, to the south of the
   Canadian cyclone.

   Steep lapse rates, associated with warm-elevated mixed-layer air
   emanating from the Mexican Plateau/Intermountain West, have already
   become confined to a plume across the southern Great Plains into
   portions of the lower Mississippi Valley.  This may become
   suppressed a bit further southward/southwestward in response to
   pattern developments today, with associated contribution to
   instability providing the primary focus for strong to severe storm
   development.

   ...Front Range/Sangre de Cristo Mountains into Red River...
   Seasonably moist southeasterly near-surface flow appears likely to
   persist into the Raton Mesa and Palmer Divide vicinities, with
   models also indicating the development of a weak surface low across
   southeastern Colorado by late afternoon.  Upslope flow, along the
   southern slopes into crest of the Palmer Divide to the north of the
   low, may contribute to intensifying thunderstorm development off the
   Front Range by late this afternoon, as mixed-layer CAPE becomes
   moderately large and inhibition weakens.  

   A few supercells are possible initially, which appear likely to
   propagate south-southeastward across southeastern Colorado into late
   evening, accompanied by a risk for large hail and potential for a
   tornado or two.  Thereafter, in the presence of strengthening
   lower/mid-tropospheric warm advection, another upscale growing and
   organizing cluster of storms is possible by late this evening, which
   may be accompanied by strong to severe surface gusts across the
   Texas/Oklahoma Panhandles into Red River vicinity by daybreak
   Sunday.

   ...Lower Mississippi into Lower Ohio Valleys vicinity...
   Convective evolution and potential is more unclear across this area.
    However, a corridor of stronger daytime heating, ahead of a remnant
   MCV, may contribute to sizable mixed-layer CAPE in excess of 2000
   J/kg by early this afternoon.  This regime may support the
   development of one or two upscale growing clusters of storms capable
   of producing potentially damaging wind gusts, while tending to
   propagate eastward and southeastward through this evening.

   ..Kerr/Thornton.. 07/08/2023

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